1. Field of the Invention
The present invention relates to a heat transfer recorder and facsimile apparatus which is capable of recording an image on a recording medium by transferring the ink on an ink sheet to the recording medium.
Examples of heat transfer recorders include facsimile apparatus, as well as other apparatuses having the function of recording such as electronic typewriters, copying apparatuses and printers.
2. Related Background Art
Heat transfer printers generally record an image by selectively heating the ink sheet used, which has a base film on which a hot-melt (or heat-subliming) ink is coated, using a thermal head in correspondence with the image signal and by transferring the melted (or sublimed) ink to recording paper. Of such heat transfer printers, in particular, heat transfer printers which employ a full-line type of thermal head record an image by driving the thermal head which is divided into blocks for the purpose of reducing the power required for driving the thermal head and the like. Further, when an image is recorded by a command to print one line, moving writing is generally employed for recording in which the time for driving the motor used for conveying recording paper is the same as the recording time for one line. However, if the recording is started from a state wherein the recording paper is completely stopped, the movement of the recording paper is slower than the movement actual recording of an image. Accordingly, a blank portion (white line) may occur in the recorded image.
FIG. 7 is a timing chart which shows the multi-scanning operation for preventing the occurrence of such a white line. In the drawing, reference numeral 70 denotes a curve which shows the distance for which recording paper is actually moved by the drive using a motor denoted by reference numeral 72. Reference numeral 71 denotes a straight line which shows the ideal moving distance of the recording paper. A thermal head is divided into four blocks. Reference numerals STB1 to STB4 respectively denote the timing charts of energization of the blocks. As seen from the drawing, in the main printing timing denoted by 72, the recording paper is not completely moved for one line and is moved .DELTA.l after the record of one line has been completed. This delay causes a problem which is common to known recording devices, where when the record of the next line is performed without any other operations, therefore, a blank portion corresponding to .DELTA.l is produced between the present line and the next line. Reference numeral S1 denotes a given moving amount of the recording paper for one line.
In order to prevent the occurrence of such a blank portion, as shown by reference numeral 73, the thermal head is energized again by using the same data while the recording paper is stopped at the same position a given time after the record of one line has been completed (referred to as "auxiliary recording" hereinafter). During this auxiliary recording, the energezation time of each of the blocks of the thermal head is shorter than that of normal image recording. As a result, the record of the image is performed in the portion denoted by .DELTA.l so that the white line can be prevented from occurring. However, such auxiliary recording is generally a technique used for recording on heat-sensitive paper, and heat-transfer printers which perform recording on recording paper by employing heat transfer particularly involve a problem with respect to the movement of the ink sheet.